On Wed, 31 Aug 2022 17:19:37 GMT, Nir Lisker <[email protected]> wrote:
>> John Hendrikx has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> Rename showing property to shown as it is already used in subclasses
>
> modules/javafx.base/src/main/java/javafx/beans/value/ObservableValue.java
> line 274:
>
>> 272: * <p>
>> 273: * Returning {@code null} from the given condition is treated the
>> same as
>> 274: * returning {@code false}.
>
> I would rephrase to use the "holds" language instead of the "return":
>
>> `{@code condition}` holding `{@code null}` is treated the same as it holding
>> {@code false}`
>
> But is this the behavior we want? I would consider throwing when the
> condition is not a `true` or `false` because it's a boolean condition.
> `orElse` can be used to create a condition that maps `null` to something else
> if the user wants to accept `null`s in the condition. I'm not sure if this is
> really a problem.
I've rephrased it as suggested.
As for `null` -- I've clarified here what it currently does (so it is not left
undefined), but I have no strong feelings either way.
I mainly choose this direction because JavaFX has so far opted to treat `null`
as something to be ignored or converted to a default value (for
`BooleanProperty`, you can set it to `null` using the generic setter, and it
would become `false`). Since the fluent system is basically built on top of
`ObjectProperty` (and thus `Object`) we can't easily exclude the possibility of
it being `null` (I have to accept `ObservableValue<Boolean>` instead of
`BooleanProperty`).
ie:
listView.layoutXProperty().setValue(null);
makes no sense at all, but JavaFX accepts it and uses `0.0`.
Ouch, just noticed it always creates (not throws) an exception (with expensive
stacktrace) whenever you do that, despite it maybe not getting logged:
@Override
public void setValue(Number v) {
if (v == null) {
Logging.getLogger().fine("Attempt to set double property to null,
using default value instead.", new NullPointerException());
set(0.0);
} else {
set(v.doubleValue());
}
}
-------------
PR: https://git.openjdk.org/jfx/pull/830
